Slide track is a familiar object in daily life. Drawer, for example, may be pulled to extend its length and pushed to return to its original position. Consequently, drawer has been widely seen in daily life.
The aforementioned slide track of a drawer should not only be able to be pulled out but also be pushed in through a labor-saving means. Consequently, the industry has been developing various types of designs for the automatic closing or returning mechanism, such that users need not to push the drawer to the end when closing the drawer; rather, the drawer can be sliding through the slide track to reach the closed position.
U.S. Pat. No. 5,207,781, for example, discloses a closing device for moving the drawer to a fully inserted position within the furniture body. The device is mounted between the furniture body and a drawer, comprising a rail member, formed by assembling a tiltable member, a guide track, and a spring, disposed on the inner wall of a furniture body and a pin member mounted on the outer wall of the drawer. The guide track comprises a rectilinear portion and an arcuate portion such that two guide rods formed from the bottom of the tiltable member can be adapted to be mounted thereupon and slide back and forth. The spring is attached with the tiltable member and the rail member on its either end. The tiltable member is disposed with a catch slot to accommodate the pin member and is further fabricated to form a beveled edge.
When the drawer is being pulled outward, the tiltable member is pulled by the pin member to move outward along the guide track and in the mean time stretch the spring. However, the tiltable member tilts when it moves to the arcuate portion of the guide track and thus the pin member will release its engagement with the tiltable member through the beveled edge, such that the drawer can be pulled outward continuously. At the point, the tiltable member is resided at the arcuate portion to prepare for the pin member to enter and reside in the catch slot through the beveled edge. When an external force is applied to the two guide rods of the tiltable member to enter the rectilinear portion of the guide track, the spring is contracted to pull the tiltable member and the pin member to return their original positions, such that the drawer can return to its closed position and close the opening of the furniture body.
Although the aforementioned invention may achieve the expected automatic closing function, some drawbacks are found and described as follows:
(1) Since the rectilinear portion and the arcuate portion of the guide track according to the aforementioned invention is L-shaped, when the tiltable member releases the engagement with the pin member, the two guide rods reside at the rectilinear portion and the arcuate portion, respectively, and the spring will exert a larger pulling force on the guide rod at the arcuate portion, such that the guide rod often fractures as a result and thus the slide track is damaged.
(2) Since there is an elevational difference between the rectilinear portion and the arcuate portion of the guide track according to the aforementioned invention, the position of the tiltable member at the arcuate portion relative to that of the tiltable member moving at the rectilinear portion will change, and thus the straight stretching of the spring becomes slant stretching, such that the returning function is negatively affected.
(3) Furthermore, to prevent the tiltable member and the pin member from abnormal disengagement in the aforementioned invention, the front of the tiltable member is protrudingly disposed with a bendable catch, such that when tiltable member moves away from its expected position, the pin member is thus pushed inward to squeeze and cross over the bendable catch. However, the vertical squeeze often causes the bendable catch to fracture accidentally, preventing the tiltable member and the pin member from engaging again and thus losing the automatic returning function.